County Democrats knew that someday, they'd have to do the unthinkable: find someone to run in Louise Slaughter's place. But any transition was never going to be clean.

Slaughter herself never gave much thought to a successor. She famously resisted the notion of preparing anyone to take over her seat, so when Slaughter died last month after a distinguished 16 terms in Congress, she left a vacuum. And politics, like nature, abhors a vacuum.

Enter State Assembly Majority Leader Joe Morelle, Brighton Town Board member Robin Reynolds Wilt, and Rochester City Council Member Adam McFadden. All three officially launched campaigns for the seat last week, setting up a potential June 26 primary.

Morelle and Wilt each framed their announcements around Slaughter, saying they're the person to carry on her progressive legacy on issues such as women's rights, health care, scientific research, voting rights, and equality. McFadden centered his message around choice.

"I think that all of us bring something different to the table, and I think the public deserves a chance to hear that and make a decision based on that," he said during an interview ahead of his announcement Friday. "It'll make the party much stronger than us just sitting back and allowing someone to walk in. We have to energize our base, and you energize the base by having open and honest discussion with choice."

Morelle clearly has the county Democratic Party establishment behind him. Brighton Supervisor Bill Moehle and Irondequoit Supervisor David Seeley attended his announcement to show support, as did some members of each town's board.

Assembly member Harry Bronson and County Clerk Adam Bello stood with Morelle at the podium, and so did Rochester Mayor Lovely Warren. Morelle has represented this community well and brought home millions of dollars for it, Warren said, and he'll be able to "hit the ground running" in Congress. She called for the party to unite behind him.

"Everyone in this room knows that Joe Morelle and I have had our political disagreements," Warren said. But, she added, they're standing "united for a common cause": making sure that Democrats keep Slaughter's seat.

Warren's backing is no small matter. Monroe County's Democratic Party is, at times, a fractured organization. And in the simplified overview often relayed by party activists and insiders, two camps have been jostling for control and influence. Warren and her allies make up one side, Morelle and his allies the other.

But the two sides seem to be at détente.

McFadden, a frequent ally of the mayor's, said he's running not because he dislikes any of the other candidates or sees them as enemies but, he reiterated, to encourage discussion and choice.

Former television news reporter Rachel Barnhart, who previously ran unsuccessfully for Assembly and Rochester mayor, is also considering a run, as is city school board President Van White. Morelle, Wilt, McFadden, White, and Barnhart are all collecting signatures for petitions, which they have to submit to the county or state Board of Elections by April 12.

The county Republican and Conservative parties are backing Dr. Jim Maxwell, a neurosurgeon who lives in East Rochester.

At his announcement, Morelle and the speakers supporting him said he'll advocate for action on gun violence, universal health care, women's rights, voting rights, and several other issues that are important to Democrats and that Slaughter prioritized. Bronson talked about Morelle's steadfast support for crucial LGBTQ anti-discrimination legislation as well as his support of the labor community.

"Joe Morelle is one of the good guys," Bronson said.

Wilt promises a grassroots campaign rooted in progressivism. She says she's concerned about many of the same issues as Morelle but says he isn't strong enough on health care. He committed to fighting for universal health care, but Wilt advocates for a single-payer system. They aren't the same thing.

Under universal health care, the government ensures that all people have access to necessary health care, regardless of their ability to pay for it. Such a system can be built around private insurance companies; Obamacare was a big step toward universal health care. Single-payer is a kind of universal health care; medical care is delivered through private providers but the government covers all medically necessary services.

Morelle hasn't signed on to sponsor an Assembly bill that would establish single-payer health care in New York, and he's previously voted against the New York Health Act, which also would have created a statewide single-payer health care system, say Wilt and Ravi Mangla, co-director of ROCitizen.

McFadden has served on City Council since 2003. He said his platform should come from the people he'd represent, though there are some issues and areas he wants to focus on: pay equality, poverty rates and their impact on education, and opportunities for jobs and entrepreneurship.

And he's "consistently been an advocate for the voiceless" on City Council, he said. He developed the Ban the Box legislation passed by Council, which prevents employers from asking about prior convictions on job applications. He also introduced legislation prohibiting income discrimination in housing.

Democrats have the enrollment advantage in the 25th Congressional District, so on paper they should be able to win, making the potential primary a crucial contest. A victory in the general election is not guaranteed, however. Democrats have an enrollment advantage county-wide, but they haven't won the county executive's seat since 1987. Real world variables, such as voter turnout, will have a decisive influence in the election.

Both Morelle and Warren have had historically strong get-out-the vote operations, and by teaming up they could be formidable.

Money will matter, too. Congressional campaigns are expensive to begin with, and this year is a high-stakes midterm year. Republicans and Democrats will wage all-out-war for control of the House, and spending will be aggressive, especially in races where there's an open seat.

Morelle has the advantage when it comes to money. He's built a network of donors that he'll be able to tap into to help fund his run, he said.

But what Morelle sees as an advantage, Wilt sees as a problem. She and her supporters point out that Morelle receives a lot of money from corporation and industry political action committees, and they disapprove. (For the record, Slaughter accepted donations from corporations, including several defense contractors.)

Wilt envisions a campaign funded by lots of small donations, not large contributions from corporations and wealthier donors. And she believes that she'd be able to get the money and people power necessary to run an effective campaign.

The developing 25th Congressional District primary is about filling a void, but it's also about the soul of a party. And that's going to mean asking how the party balances its core ideals, its differing philosophies, and the reality that under the current system, big elections require massive resources.

For Monroe County Democrats, the hard part will be airing these questions while preserving the party's fragile peace.